Diversidade e aplicações biotecnológicas de fungos endofíticos associados à espécies da sub-família Mirtoideae (Myrtaceae) presentes em ecossistemas do Brasil, Argentina e Espanha

Abstract

Endophytic fungi inhabit healthy plant tissues during at least one stage of their life cycle without causing any apparent symptom of disease or negative effects on the hosts. In the last years, the endophytic fungal mycota associated with popular medicinal plants have been perfomed because some medicinal properties have been associated to secondary metabolities production by their endophytic fungi associated. Fungal endophyte communities associated with leaves of Myrciaria floribunda, Alchornea castaneifolia, and Eugenia aff. bimarginata were examined, collected from Brazilian Cerrado ecosystems, and studied for their ability to produce antimicrobial activity. A total of 93 isolates of endophytic fungi were obtained and identified by sequencing of internal transcribed spacer (ITS) regions of the rRNA gene. Thirty-eight fungal extracts presented antimicrobial activity against at least one of the different target microorganisms tested. The biogeography of microorganisms is poorly understood and to to address whether patterns of endophyte diversity are correlated with host phylogeny, environmental variables and distance we designed a geographic survey of related host tree of Myrtae tribe. The study was performed at the following spatial scales: regional, 101-5,000 km; local: 0-100 km and microscale: 0-1 km. A total of 960 isolates of endophytic fungi were obtained from 3,000 leaf fragment samples. These isolates were grouped and identified into 52 species. We found that the similarity of endophytic fungal communities decreases with increasing geographical distance, showed by the distance decay analysis. The nonmetric multidimensional scaling (NMDS) analysis showed that the fungal endophytes communities were grouped at a local scale. The multiple regression on matrices (MRM) suggested that the fungal endophytic community similarity depends on the scale sampled used. Other study showed that endophytic fungi can interact with arbuscular micorryzal, increasing the growth plant. A total of 150 isolates of endophytic fungi were obtained from roots of Myrtus communis and seven groups were selected to interactions study with Sorghum vulgare. None of the root endophytic fungi tested colonized the root of sorghum, but significantly increased the growth and arbuscular mycorrhizal colonization of sorghum. The fourth part of this work evaluated the endophytic community diversity of Myrtus communis by classical isolation from leaves fragments and denaturing gel gradient electrophoresis (DGGE). A total of 113 fungal isolates were obtained and identified by classical isolation in potato dextrose agar. It was found that the similarity of endophytic fungal communities did not decrease with increasing geographical distance. The results obtained in this work suggest a high endophytic fungal diversity associated with Myrtaceae host tree presents indifferent ecossistems. Moreover, these micro-organismos represents a potencial source of substances that can be used to development of new antimicrobial drugs and as a growth promoting fungi.